what is a literature search used for

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• Indian J Anaesth
• v.60(9); 2016 Sep

Literature search for research planning and identification of research problem

Anju grewal.

Department of Anaesthesiology, Dayanand Medical College and Hospital, Ludhiana, Punjab, India

Hanish Kataria

1 Department of Surgery, Government Medical College and Hospital, Chandigarh, India

2 Department of Cardiac Anaesthesia, All India Institute of Medical Sciences, New Delhi, India

Literature search is a key step in performing good authentic research. It helps in formulating a research question and planning the study. The available published data are enormous; therefore, choosing the appropriate articles relevant to your study in question is an art. It can be time-consuming, tiring and can lead to disinterest or even abandonment of search in between if not carried out in a step-wise manner. Various databases are available for performing literature search. This article primarily stresses on how to formulate a research question, the various types and sources for literature search, which will help make your search specific and time-saving.

INTRODUCTION

Literature search is a systematic and well-organised search from the already published data to identify a breadth of good quality references on a specific topic.[ 1 ] The reasons for conducting literature search are numerous that include drawing information for making evidence-based guidelines, a step in the research method and as part of academic assessment.[ 2 ] However, the main purpose of a thorough literature search is to formulate a research question by evaluating the available literature with an eye on gaps still amenable to further research.

Research problem[ 3 ] is typically a topic of interest and of some familiarity to the researcher. It needs to be channelised by focussing on information yet to be explored. Once we have narrowed down the problem, seeking and analysing existing literature may further straighten out the research approach.

A research hypothesis[ 4 ] is a carefully created testimony of how you expect the research to proceed. It is one of the most important tools which aids to answer the research question. It should be apt containing necessary components, and raise a question that can be tested and investigated.

The literature search can be exhaustive and time-consuming, but there are some simple steps which can help you plan and manage the process. The most important are formulating the research questions and planning your search.

FORMULATING THE RESEARCH QUESTION

Literature search is done to identify appropriate methodology, design of the study; population sampled and sampling methods, methods of measuring concepts and techniques of analysis. It also helps in determining extraneous variables affecting the outcome and identifying faults or lacunae that could be avoided.

Formulating a well-focused question is a critical step for facilitating good clinical research.[ 5 ] There can be general questions or patient-oriented questions that arise from clinical issues. Patient-oriented questions can involve the effect of therapy or disease or examine advantage versus disadvantage for a group of patients.[ 6 ]

For example, we want to evaluate the effect of a particular drug (e.g., dexmedetomidine) for procedural sedation in day care surgery patients. While formulating a research question, one should consider certain criteria, referred as ‘FINER’ (F-Feasible, I-Interesting, N-Novel, E-Ethical, R-Relevant) criteria.[ 5 ] The idea should be interesting and relevant to clinical research. It should either confirm, refute or add information to already done research work. One should also keep in mind the patient population under study and the resources available in a given set up. Also the entire research process should conform to the ethical principles of research.

The patient or study population, intervention, comparison or control arm, primary outcome, timing of measurement of outcome (PICOT) is a well-known approach for framing a leading research question.[ 7 , 8 ] Dividing the questions into key components makes it easy and searchable. In this case scenario:

• Patients (P) – What is the important group of patients? for example, day care surgery
• Intervention (I) – What is the important intervention? for example, intravenous dexmedetomidine
• Comparison (C) – What is the important intervention of comparison? for example, intravenous ketamine
• Outcome (O) – What is the effect of intervention? for example, analgesic efficacy, procedural awareness, drug side effects
• Time (T) – Time interval for measuring the outcome: Hourly for first 4 h then 4 hourly till 24 h post-procedure.

Multiple questions can be formulated from patient's problem and concern. A well-focused question should be chosen for research according to significance for patient interest and relevance to our knowledge. Good research questions address the lacunae in available literature with an aim to impact the clinical practice in a constructive manner. There are limited outcome research and relevant resources, for example, electronic database system, database and hospital information system in India. Even when these factors are available, data about existing resources is not widely accessible.[ 9 ]

TYPES OF MEDICAL LITERATURE

(Further details in chapter ‘Types of studies and research design’ in this issue).

Primary literature

Primary sources are the authentic publication of an expert's new evidence, conclusions and proposals (case reports, clinical trials, etc) and are usually published in a peer-reviewed journal. Preliminary reports, congress papers and preprints also constitute primary literature.[ 2 ]

Secondary literature

Secondary sources are systematic review articles or meta-analyses where material derived from primary source literature are infererred and evaluated.[ 2 ]

Tertiary literature

Tertiary literature consists of collections that compile information from primary or secondary literature (eg., reference books).[ 2 ]

METHODS OF LITERATURE SEARCH

There are various methods of literature search that are used alone or in combination [ Table 1 ]. For past few decades, searching the local as well as national library for books, journals, etc., was the usual practice and still physical literature exploration is an important component of any systematic review search process.[ 10 , 11 ] With the advancement of technology, the Internet is now the gateway to the maze of vast medical literature.[ 12 ] Conducting a literature review involves web-based search engines, i.e., Google, Google Scholar, etc., [ Table 2 ], or using various electronic research databases to identify materials that describe the research topic or those homologous to it.[ 13 , 14 ]

Methods of literature search

Web based methods of literature search

The various databases available for literature search include databases for original published articles in the journals [ Table 2 ] and evidence-based databases for integrated information available as systematic reviews and abstracts [ Table 3 ].[ 12 , 14 ] Most of these are not freely available to the individual user. PubMed ( http://www.ncbi.nlm.nih.gov/pubmed/ ) is the largest available resource since 1996; however, a large number of sources now provide free access to literature in the biomedical field.[ 15 ] More than 26 million citations from Medline, life science journals and online books are included in PubMed. Links to the full-text material are included in citations from PubMed Central and publisher web sites.[ 16 ] The choice of databases depends on the subject of interest and potential coverage by the different databases. Education Resources Information Centre is a free online digital library of education research and information sponsored by the Institute of Education Sciences of the U.S. Department of Education, available at http://eric.ed.gov/ . No one database can search all the medical literature. There is need to search several different databases. At a minimum, PubMed or Medline, Embase and the Cochrane central trials Registry need to be searched. When searching these databases, emphasis should be given to meta-analysis, systematic reviews randomised controlled trials and landmark studies.

Electronic source of Evidence-Based Database

Time allocated to the search needs attention as exploring and selecting data are early steps in the research method and research conducted as part of academic assessment have narrow timeframes.[ 17 ] In Indian scenario, limited outcome research and accessibility to data leads to less thorough knowledge of nature of research problem. This results in the formulation of the inappropriate research question and increases the time to literature search.

TYPES OF SEARCH

Type of search can be described in different forms according to the subject of interest. It increases the chances of retrieving relevant information from a search.

Translating research question to keywords

This will provide results based on any of the words specified; hence, they are the cornerstone of an effective search. Synonyms/alternate terms should be considered to elicit further information, i.e., barbiturates in place of thiopentone. Spellings should also be taken into account, i.e., anesthesia in place of anaesthesia (American and British). Most databases use controlled word-stock to establish common search terms (or keywords). Some of these alternative keywords can be looked from database thesaurus.[ 4 ] Another strategy is combining keywords with Boolean operators. It is important to keep a note of keywords and methods used in exploring the literature as these will need to be described later in the design of search process.

‘Medical Subject Heading (MeSH) is the National Library of Medicine's controlled hierarchical vocabulary that is used for indexing articles in PubMed, with more specific terms organised underneath more general terms’.[ 17 ] This provides a reliable way to retrieve citations that use different terminology for identical ideas, as it indexes articles based on content. Two features of PubMed that can increase yield of specific articles are ‘Automatic term mapping’ and ‘automatic term explosion’.[ 4 ]

For example, if the search keyword is heart attack, this term will match with MeSH transcription table heading and then explode into various subheadings. This helps to construct the search by adding and selecting MeSH subheadings and families of MeSH by use of hyperlinks.[ 4 ]

We can set limits to a clinical trial for retrieving higher level of evidence (i.e., randomised controlled clinical trial). Furthermore, one can browse through the link entitled ‘Related Articles’. This PubMed feature searches for similar citations using an intricate algorithm that scans titles, abstracts and MeSH terms.[ 4 ]

Phrase search

This will provide pages with only the words typed in the phrase, in that exact order and with no words in between them.

Boolean operators

AND, OR and NOT are the three Boolean operators named after the mathematician George Boole.[ 18 ] Combining two words using ‘AND’ will fetch articles that mention both the words. Using ‘OR’ will widen the search and fetch more articles that mention either subject. While using the term ‘NOT’ to combine words will fetch articles containing the first word but not the second, thus narrowing the search.

Filters can also be used to refine the search, for example, article types, text availability, language, age, sex and journal categories.

Overall, the recommendations for methodology of literature search can be as below (Creswell)[ 19 ]

• Identify keywords and use them to search articles from library and internet resources as described above
• Search several databases to search articles related to your topic
• Use thesaurus to identify terms to locate your articles
• Find an article that is similar to your topic; then look at the terms used to describe it, and use them for your search
• Use databases that provide full-text articles (free through academic libraries, Internet or for a fee) as much as possible so that you can save time searching for your articles
• If you are examining a topic for the first time and unaware of the research on it, start with broad syntheses of the literature, such as overviews, summaries of the literature on your topic or review articles
• Start with the most recent issues of the journals, and look for studies about your topic and then work backward in time. Follow-up on references at the end of the articles for more sources to examine
• Refer books on a single topic by a single author or group of authors or books that contain chapters written by different authors
• Next look for recent conference papers. Often, conference papers report the latest research developments. Contact authors of pertinent studies. Write or phone them, asking if they know of studies related to your area of interest
• The easy access and ability to capture entire articles from the web make it attractive. However, check these articles carefully for authenticity and quality and be cautious about whether they represent systematic research.

The whole process of literature search[ 20 ] is summarised in Figure 1 .

Process of literature search

Literature search provides not only an opportunity to learn more about a given topic but provides insight on how the topic was studied by previous analysts. It helps to interpret ideas, detect shortcomings and recognise opportunities. In short, systematic and well-organised research may help in designing a novel research.

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Learning Objectives

(1) Explain steps in conducting a literature search

(2) Identify resources to utilize in a literature search

(3) Perform an online literature search using U of U Health resources

Valentina is a third year pediatric resident who notices that many of the teenagers she sees in clinic use their phones to play games and connect with friends and family members. She wonders if there could be an app for teenagers to manage their chronic diseases, specifically type 1 diabetes. But where does she begin? 

What is a literature search?

iterature search is a comprehensive exploration of published literature with the purpose of finding scholarly articles on a specific topic . Managing and organizing selected scholarly works can also be useful.

Why do a literature search?

Literature search is a critical component for any evidence-based project. It helps you to understand the complexity of a clinical issue, gives you insight into the scope of a problem, and provides you with best treatment approaches and the best available evidence on the topic. Without this step, your evidence-based practice project cannot move forward.

Five steps for literature search success

There are several steps involved in conducting a literature search. You may discover more along the way, but these steps will provide a good foundation. 

Plan using PICO(T) to develop your clinical question and formulate a search strategy.

Identify a database to search.

Conduct your search in one or more databases.

Select relevant articles .

Organize your results . Remember that searching the literature is a process.

#1: Plan using PICO(T)

The PICO(T) question framework is a formula for developing answerable, researchable questions. Using PICO(T) guides you in your search for evidence and may even help you be more efficient in the process ( Click here to learn all about PICO(T) ). 

Once you have your PICO(T) question you can formulate a search strategy by identifying key words, synonyms and subject headings. These can help you determine which databases to use. 

#2: Identify a database

For your search, you will need to consult a variety of resources to find information on your topic. While some of these resources will overlap, each also contains unique information that you won’t find in other databases.  

The "Big 3" databases: Embase, PubMed, and Scopus are always important to search because they contain large numbers of citations and have a fairly broad scope. ( Click here to access these databases and others in the library's A to Z database.) 

In addition to searching these expansive databases, try one that is more topic specific.

We are here to help.

If you are conducting a literature search and are not certain of the details, don't panic! U of U Health has a wealth of resources, including experienced librarians, to help you through the process. Learn more here. 

Utah’s Epic-embedded librarian support

Did you know you can request evidence-based information from the library directly through Epic?  Contact us through Epic’s Message Basket.

Eccles Health Sciences medical librarians are able to provide expertise in articulating the clinical question, identifying appropriate data sources, and locating the best evidence in the shortest amount of time. You can also send a message to ASK EHSL .

#3: Conduct your search

Now that you have identified pertinent databases, it is time to begin the search!

Use the key words that you’ve identified from your PICO(T) question to start searching. You might start your search broadly, with just a few key words, and then add more once you see the scope of the literature. If the initial search doesn't produce many results, you can play with removing some key words and adding more granular detail.

In our intro case study, Valentina’s population is teenagers with type 1 diabetes and her intervention is a mobile app. Watch the video below to see how Valentina uses the powerful Embase PICO search feature to identify synonyms for type 1 diabetes, mobile apps, and teenagers.

Example of   Embase using PICO Why use Embase? This search casts a wider net than most databases for more results.

Common Search Terms and Symbols

AND Includes both keywords Narrows search OR Either keyword/concept Combine synonyms and similar concepts Expands search "Double quotes"  Specific phrase Wildcard* Any word ending variants (singular, plural, etc.) Example: nurs* = nurse, nurses, nursing, etc.

Controlled Vocabulary

Want to help make your search more accurate? Try using the controlled vocabulary, or main words or phrases that describe the main themes in an article, within databases. Controlled vocabulary is a standardized hierarchical system. For example, PubMed uses Medical Subject Headings or MeSH terms to “map” keywords to the controlled vocabulary. Not all databases use a controlled vocabulary, but many do. Embase’s controlled vocabulary is called Emtree, and CINAHL’s  controlled vocabulary is called CINAHL Headings. Consider focusing the controlled vocabulary as the major topic when using MeSH, Emtree, or CINAHL Headings. 

For Valentina’s question, there are MeSH terms for Adolescent, Diabetes Mellitus, Type 1, and Mobile Applications.

Example of  PubMed using MeSH MeSH helps focus your PubMed search

Talk with your librarians for more help with searching with controlled vocabularies. 

Every database uses filters to help you narrow your search. There are different filters in each database, but they tend to work in similar ways. Use filters to help you refine your search, rather than adding those keywords to the search. Filters include article/publication type, age, language, publication years, and species.

Using filters can help return the most accurate results for your search.

Article/publication types, such as randomized controlled trial, systematic reviews, can be used as filters.

Use an Age Filter, rather than adding “pediatric” or “geriatric” to your search.

Valentina uses the age filter for her question rather than as a keyword in the video below.

Example of a PubMed keyword search using filters PubMed is the most common search because it is the most widely available.

#4: Select relevant articles

Once you have completed your search, you’ll select articles that are relevant to your question. Some databases also include a “similar articles” feature which recommends other articles similar to the article you’re reviewing—this can also be a helpful tool.

When you’ve identified an article that appears relevant to your topic, use the “Snowballing” technique to find additional articles. Snowballing involves reviewing the reference lists of articles from your search. 

In other words, look at your key articles and review their reference list for additional key or seminal articles to aid in your search.

#5: Organize your results

As you begin to collect articles during your literature search, it is important to store them in an organized fashion. Most research databases include personalized accounts for storing selected references and search strategies. 

Reference managers are a great way to not only keep articles organized, but they also generate in-text citations and bibliographies when writing manuscripts, and provide a platform for sharing references with others working on your project.

A number of reference managers—such as Zotero , EndNote , RefWorks, Mendeley , and Papers are available. EndNote Basic (web-based) is freely available to U of U faculty, staff and students. If you need help with this process, contact a librarian to help you select the reference manager  that will best suit your needs.

Using these steps, you’re ready to start your literature search. It is important to remember that there is not a right or wrong way to do the search. Literature searches are an iterative process—it will take some time and negotiation to find what you are looking for. You can always change your approach, or the information resource you are using. The important thing is to just keep trying. And before you get frustrated or give up, contact a librarian . They are here to help!

This article originally appeared May 12, 2020. It was updated to reflect current practice on March 14, 2021.

Tallie Casucci

Barbara wilson.

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Q. What is a literature search? What can I expect when I request one?

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Answered By: KRS Answers Last Updated: Oct 19, 2023     Views: 2952

A literature search is the methodical investigation of formally or informally published sources of information about a particular topic or question. A KRS Team Member provides a comprehensive list of literature with no analysis or summarization and can include the search strategy as part of the final product.  

What are the different types of literature searches, and what timelines are associated with each?

Urgent patient care searches.

What is an urgent patient care search?  A literature search that is urgently needed to provide information for direct patient care

What can I expect? An urgent patient care search is completed within the same business day. Our hours of operation are 8:00 a.m. to 4:00 p.m. Monday to Friday .

Non-urgent patient care searches

What is a non-urgent patient care search?  A literature search that is directly related to patient care but is not needed within the same business day. The information gained from these searches is used to directly influence patient care by impacting assessment, diagnosis, treatment, or management.

What can I expect? After the initial contact, a standard search is normally completed within 5 business days . Different timelines may be negotiated depending up on the complexity and scope of the search.

Indirect patient care searches

What is an indirect patient care search? A literature search that is not directly or immediately related to patient care. The information gained from these searches is used to inform practice guidelines, policy development, administrative decisions, or ongoing research.

What can I expect? After initial contact, a non-patient care search is normally completed within 10 business days .  As non-patient care searches require a longer timeline due to their complexity and the need to search a greater variety of resources including AHS policies and procedures, grey literature, and published literature

Complex searches

What are complex searches? Complex searches include, but are not limited to: systematic reviews, Strategic Clinical Questions, and other large scale projects. 

What can I expect? Complex searches often take longer than 10 business days to complete due to the scope and breadth of the project or topic.  As such, these large-scale requests are handled on a case-by-case basis, and are assigned to a KRS searcher according to availability/capacity.  After the search request is received and identified as complex, the KRS team member responsible for conducting the search will contact you to negotiate timelines and other details. KRS librarians will not search any databases we do not license; it is the responsibility of the requestor to complete literature searches in non AHS licensed databases.

After you request a literature search: 

• Within two business days, you will be contacted by a KRS team member who will be working on your search.  If your search request is for urgent patient care, a KRS searcher will contact you the same business day.  

Additional factors that may need to be reviewed include:

• the level of detail provided in your request
• the deadline you have provided
• the nature, scope and complexity or your search topic
• the potential variety of sources of information to be searched to meet your needs
• how you would like the literature search results organized
• how the results will be used
• and possible overlaps and linkages with other work already underway or completed in AHS.

The standard literature search summary in the reply will contain:

• Resources consulted in completing the search
• Limits imposed, such as date ranges
• Search strategy used 
• Other details relevant to your specific search

Standard literature search results will include:

• Full citations for all references included
• Article abstracts where available
• Links to articles where full text is available
• Your KRS searcher will follow up with you upon completion of the search, to see if further or different work is required and to provide you with an opportunity to provide feedback on the completed search.

Literature searching is subject to the limitations of the database(s), website(s), and other resources licensed and searched. Our literature search service involves sourcing accurate and authoritative information. However, we do not interpret the evidence provided. If critical appraisal assistance is needed, we can direct you to helpful tools and resources or put you in touch with experts on the topic.

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A literature search is a systematic, thorough search of a range of literature (for example books, peer-reviewed articles, etc.) on your topic. Commonly you will be asked to undertake literature searches as part of your Level 3 and postgraduate study.

It is important before undertaking any research to fully understand the shape of the literature in the area. Literature searching can be broken down into a series of iterative steps. You may want to revisit some of these several times throughout your search.

Planning your search

What to search for: keywords and phrases.

Start the process by clarifying the research question you would like answered. Your next step is to use your research question to help you identify keywords. The language and terminology of your subject area will help you to identify the most effective words for your search.

You can also identify keywords by looking for background information on key areas within your topic online as this will give you ideas for synonyms and other words commonly used.

The activity on  Choosing good keywords  will provide further guidance. 

Where to search: Library Search, Databases and Google Scholar

Now that you have your keywords you need to decide where to search. Library Search is a good starting point, particularly for unfamiliar topics, to provide background information and lead to further sources. 

No two databases include exactly the same content. It is therefore advisable to search several databases to make sure you do not miss a key paper on your topic. If you are unsure where to search, the Selected resources for your study page will help you find the most relevant databases. 

You may also like to use Google Scholar, which will search a wider set of resources, including items not available through the OU Library. Google Scholar  offers more guidance on how to access eresources. It also has instructions on how to add the "Find it at OU" button to Google Scholar search results.

Search techniques

Once you have your keywords you will need to combine them. You can use the help sheet on  Advanced search techniques as guidance. You may also find the following activities useful:

The Library online training session on  Smarter searching with library databases .

The activity on Filtering information quickly .

Further reading:

Byrne, D. (2017).  Developing a researchable question .  Project Planner . Sage Research Methods. DOI:10.4135/9781526408525. 

Byrne, D. (2017). Reviewing the literature .  Project Planner . Sage Research Methods. DOI:10.4135/9781526408518. 

Evaluating information

It is important to evaluate the literature you find for quality and relevance. The PROMPT criteria will help with this. You can consult the  Evaluating the quality of information (requires login)  activity for further guidance.

Organising information

When conducting a literature search recording the information you find in an organised manner is essential. Literature searches require you to read and keep track of many more articles than you would read for an assignment. You may want to try using a bibliographic management tool to help organise the references you have found. The library page on Bibliographic management will help you understand the different tools available.

The Library's Organising information activity will help you understand why it is important to organise information. It will also explain what referencing means and why it is so important.

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Best Practice for Literature Searching

• Literature Search Best Practice

What is literature searching?

• What are literature reviews?
• Hierarchies of evidence
• 1. Managing references
• 2. Defining your research question
• 3. Where to search
• 4. Search strategy
• 5. Screening results
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Literature searching is the task of finding relevant information on a topic from the available research literature. Literature searches range from short fact-finding missions to comprehensive and lengthy funded systematic reviews. Or, you may want to establish through a literature review that no one has already done the research you are conducting. If so, a comprehensive search is essential to be sure that this is true.

Whatever the scale, the aim of literature searches is to gain knowledge and aid decision-making.  They are embedded in the scientific discovery process. Literature searching is a vital component of what is called "evidence-based practice", where decisions are based on the best available evidence.

What is "literature"?

Research literature writes up research that has been done in order to share it with others around the world. Far more people can read a research article than could ever visit a particular lab, so the article is the vehicle for disseminating the research.  A research article describes in detail the research that's been done, and what the researchers think can be concluded from it.   

It is important, in literature searching, that you search for  research literature .  Scientific information is published in different formats for different purposes: in  textbooks  to teach students; in  opinion  pieces, sometimes called  editorials  or  commentaries , to persuade peers; in  review articles  to survey the state of knowledge.  An abundance of other literature is available online, but not actually published (by an academic publisher)--this includes things like  conference proceedings ,  working papers, reports  and  preprints .  This type of material is called grey (or gray) literature . 

Most of the time what you are looking for for your literature review is research literature (and not opinion pieces, grey literature, or textbook material) that has been published in  scholarly peer reviewed journals .

As expertise builds, using a greater diversity of literature becomes more appropriate.  For instance, advanced students might use conference proceedings in a literature review to map the direction of new and forthcoming research. The most advanced literature reviews, systematic reviews, need to try to track down unpublished studies to be comprehensive, and a great challenge can be locating not only relevant grey literature, but studies that have been conducted but not published anywhere.  If in doubt, always check with a teacher or supervisor about what type of literature you should be including in your search.   

Why undertake literature searches?

By undertaking regular literature searches in your area of expertise, or undertaking complex literature reviews, you are:

• Able to provide context for and justify your research
• Exploring new research methods
• Highlighting gaps in existing research
• Checking if research has been done before
• Showing how your research fits with existing evidence
• Identifying flaws and bias in existing research
• Learning about terminology and different concepts related to your field
• Able to track larger trends
• Understanding what the majority of researchers have found on certain questions.
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Educational resources and simple solutions for your research journey

Differences between literature search and literature review

You’ve just found out you need to do a literature review. You know the term literature search, but you’re not sure what the difference is between a literature search and a literature review. This can be confusing if you’re just starting out in academia. Although literature search and review are related terms, they refer to different processes and functions. In general, a literature search is the process of seeking out and identifying the existing literature related to a topic or question of interest, while a literature review is the organized synthesis of the information found in the existing literature.

In research applications, a literature search is typically the first step of a literature review. The search identifies relevant existing studies and articles, and the review is the end result of analyzing, synthesizing, and organizing the information found in the search. The following summarizes the literature search and review concepts as researchers typically practice them.

Literature search

A literature search is a systematic search for existing information on your question or topic 1 . The purpose of a literature search is to aid in the formulation of a research question and study design. When you are planning to conduct a study on a specific topic, the literature search helps narrow the focus of your study by identifying areas in which knowledge gaps exist. The search of existing studies can also guide the research design by suggesting appropriate methodologies and important variables. Research studies are never done in a vacuum – they are built on previous knowledge. A comprehensive literature search and review will provide you the base on which to build your study.

An effective search needs to be planned. Here are some tips for conducting a literature search 4 .

• Identify key words to use when searching through library and internet resources.
• Search multiple databases for relevant articles, books, and other scholarly writings.
• Use articles similar to your proposed study to find additional keywords.
• Start with the most recent articles and work backward in time if necessary.
• Include conference papers in your search as they generally represent the latest research.
• Cast a wide net by searching in databases that might be unrelated to your topic.
• Keep in mind that literature searches are iterative processes. Find new key words and articles through the references and citations in other relevant sources.
• Make sure to document all of the articles you identify as relevant to your topic. This will save you time and frustration later when you want to find them again and when you need to write references for your literature review.

In a literature review, the results of a literature search are used to produce an organized and coherent presentation of the relevant knowledge about a specific topic. This is accomplished through reviewing, evaluating, analyzing, and synthesizing the information found through a search. An effective literature review clearly places the proposed study in the context of previous research studies and identifies a gap in the knowledge that will be addressed by the proposed study.

A good literature review serves to demonstrate the depth of your knowledge and understanding of the topic; it is not simply a summary or description of those studies 2 . Here are some tips in conducting an effective literature review process.

• Identify a wide range of articles using a literature search.
• Evaluate those articles to determine which are relevant to your review 2 . When evaluating the research, include considerations such as the significance of the study, the methodology, the value of the analysis, the structure of the article, and the overall effectiveness of the study.
• Analyze the articles you’ve chosen to include. Critically and objectively review the study’s methods, results, and conclusions. Look for strengths and weaknesses. What can you learn from this study as it relates to your work?
• Synthesize the information from all of the included sources. Look for patterns in the articles. What do they agree on? What do they disagree on? What is missing from the information?
• Organize your literature review based on chronology, methodology, or themes. Again, this should not be merely a listing of the literature but a carefully structured whole.
• Write your literature review using the format of an introduction, body, and conclusion.

Additional tips for researchers

• Always strive for objectivity when conducting a literature search or review. Include all viewpoints and do not begin the process expecting a specific result. Avoid opinions.
• Make sure your selected sources and your literature review work to place your study in the context of the existing literature.
• The literature should reveal a knowledge gap that will be addressed by your study.
• As with all writing, keep your audience in mind.

Table of Contents

• Grewal A, Kataria H, Dhawan I. Literature search for research planning and identification of research problem. Indian J Anaesth. 2016, 60, 635-639. doi: 10.4103/0019-5049.190618.
• Niagara University Library Research Guide. Literature Review. https://niagara.libguides.com/litreview/sixsteps [Accessed August 31, 2022]

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How to undertake a literature search

Introduction.

Undertaking a literature search can be a daunting prospect. By breaking the exercise down into smaller steps, you can make the process more manageable. The following ten steps will help you complete the task from identifying key concepts to choosing databases for your search and saving your results and search strategy. It discusses each of the steps in a little more detail with examples and suggestions of where to get help.

There are ten steps to undertaking a literature search which we'll take you through below:

🎬 - Indicates a video is available with more information.

Please click on the boxes below to get a bit more detail on each step.

First, write out your title and check that you understand all the terms. Look up the meaning of any you don’t understand. An online dictionary or medical encyclopaedia may help with this.

If your search is for a dissertation, you may need to choose your own research question. In this case, you will need to consider whether there is likely to be enough research on your topic. Alternatively, if your topic is too broad, you could be overwhelmed by the number of references.

One way of checking how much is written on your topic is to use Library Search. Most libraries offer a Library Search or discovery tool. It provides a quick search across all the library’s holdings. You can also limit your search by date or type of document. If you just need a few references to help you write an essay, Library Search may be helpful. It also gives quick access to full text items.

Next, you need to identify your key concepts. One way to do this is to look at your title and identify the most important words. Ignore words that tell you what to do with the information you find eg evaluate, assess, compare, as these are not generally used as search terms. In the example below, key concepts have been highlighted:

Evaluate the effectiveness of a mindfulness intervention on the health-related quality of life of rheumatoid arthritis patients

Another way to do this is to break down your title using the PEO framework:

P = Population    E = Exposure    O = Outcome 

This works well where there is no comparison between two types of treatment or intervention.

In our example:

P = rheumatoid arthritis patients

E = mindfulness

O =  health related quality of life

Other question formats are available such as PICO or SPIDER

Tip: Not all search topics will include every element of PICO – some include fewer items.

Once you have identified the key concepts, it’s important to think of any other terms or phrases that might have a very similar meaning. Including such synonyms will make your search as thorough as possible. For example, if your topic is looking for articles on Staff attitudes , you might also use the terms:

• Staff perceptions 
• Staff opinions
• Stereotyping
• Labelling 

If the database you are using has a list of subject heading s , this may help you to find the most appropriate term for your subject. Some databases provide definitions for terms used in the database and may suggest related terms.

A comprehensive search will usually include both subject headings from databases and terms that you have thought of yourself.

Tip: Often your search term will be a phrase instead of a single word. To carry out phrase searches, use double quotes, for example “problem drinking”.

Once you have chosen your search terms, you need to think about the best databases for your topic. The databases you choose will depend on the search question and the libraries you have access to.

Tip: It’s well worth taking a few minutes to get to know the databases available on the Library webpages and what they cover.

The next step is to combine your search terms in such a way that you only retrieve the more relevant references for your search question. In order to do this you need to build a search strategy . This involves using Boolean operators such as AND , OR and NOT .

AND narrows the results of the search by ensuring that all the search terms are present in the results. 

OR broadens the results of the search by ensuring that any of the search terms are present in the results.

NOT limits the results by rejecting a particular search term. Be careful with NOT because it will exclude any results containing that search term regardless of whether other parts of the article might have been of interest.

OR will broaden your number of results while AND will produce fewer results.

Try using this  Search-plan-worksheet   to break your topic down into concepts. These can then be linked together when you run the search. You can also add synonyms within each concept box. The yellow limits box is a prompt to think about any limits you want to apply when searching. This leads us to Step 6.

Tip: Most databases will allow you to use a truncation sign (*) or wildcard (?) to pick up various different endings to words or alternative spellings.

For example:  alcohol* would pick up alcohol, alcoholic, alcoholism, etc

Sm?th would find Smith and Smyth

The next step is to think about any other restrictions you want to make to your results.

Common limiters found on databases include:

• Peer reviewed articles
• Research articles
• Age group (adult, child, older person)
• Document type

Not all databases allow all of the limiters above.

When writing a dissertation, primary research articles are normally required. Where the database allows you, try limiting to research articles only.

Non-research materials can also be useful as an overview of your topic; for example a literature review can give an analysis of what has already been written on a topic.

The video below includes a demonstration of how limits can be applied using the CINAHL database as an example:

CINAHL - advanced

Once you have identified all your search terms and any limits you want to apply, you are ready to run your search on the databases you have chosen. 

Once you have some search results, you can look through them and start to select those that look relevant to your literature search. It is likely you will reject some because they are not quite what you wanted but there will be others that can be marked for further attention.

The title of an article on its own may not tell you very much; read the abstract quite carefully to see if the article is relevant or not.

Tip: You can show more details for each record by clicking on the article title. On some databases, there may be an abstract for the article which you can open. 

If you find you are either generating more results than you can possibly look at or too few results to write about, be prepared to adjust your search terms and the way they are combined.

If you get too many results you could try: •limiting to just the most recent material •adding another term or concept and linking it using “AND” •limiting to a particular country or geographical area such as UK

If you get too few results, you might try: •expanding your date range •removing any geographical limits you have applied  •removing the least important term or concept

Tip: Be prepared to try other databases and keep searching until you feel confident you have found enough relevant material.

Once you have selected some articles that look relevant for your piece of work, you will need to save them so that your hard work is not wasted.

At the same time, you will want to save your search strategy . This is a record of the terms you searched, how you combined them, any limits you applied and how many results you found.

You will also need to choose a way to save your results. One way is to email the results to yourself and this can be done from all the databases .

Another way is to export your results to reference management software such as Zotero, RefWorks, EndNote or Mendeley. This software allows you to collect, organise and cite research. It is suitable for managing references over a long period of time. 

The RCN Library and Archive Service provides help with using Zotero . 

Tip: Keep a record of all the databases you use as you carry out your search. It is also a good idea to note where you found any references you subsequently use for your dissertation.

The final step is to obtain the full text of the articles identified in your search which you believe may be useful for your assignment. If you are lucky, many of these will be available electronically and you may just be able to follow a link to the full text.

Alternatively you can copy and paste your article title into the Library search box  and if it is available as full text, a hyperlink will be shown which will link you to the document.

If you are studying elsewhere and have access to a university or hospital library, they may subscribe to different journals to the RCN Library so it is worth exploring what they can offer. If your library does not have either an electronic copy or a physical copy, you may need to request the article by interlibrary loan .

Tip: It is also worth using Google or other browsers to check for the article title you require. Sometimes the article has been made freely available on the internet by the authors.

Boolean operators – words (AND, OR and NOT) which can be used to combine search terms in order to widen or limit the search results.

Database – this is an online collection of citations to journal articles which have been indexed to make retrieval easier. Some databases which also provide full text access to the articles.

Limits – these are options within a database which allow search results to be broken down further. Common limits are year(s) of publication, document type and language. MEDLINE and CINAHL allow age limits too.

Search Strategy – the list of search terms and limits used to retrieve relevant articles from a database in order to answer a search question.

Subject headings – terms that have been assigned to describe a concept that may have many alternative keywords. All these alternative keywords or terms are brought together under the umbrella of this single term. Most health-related databases use subject headings.

Additional information

If after following these steps, you still can’t find what you are looking for, remember that there is always help available at your library. The RCN Library and Archives Service offers a range of help materials via our Literature searching and training pages . These include: • Databases guides in electronic and printed formats • Video tutorials on how to search the databases • 1-1 training sessions pre-bookable via the RCN website face to face or via zoom

A subject guide is also available on Doing your dissertation which provides suggestions for key resources, books and journal articles which may help. Click on the link below to access this guide:

Doing your dissertation subject guide

Here are other resources you may also find helpful. You will find links to each resource below too:

• Aveyard H (2019) Doing a literature review in health and social care: a practical guide . 4th edn. London: Open University Press.
• Bettany-Satlikov J (2016) How to do a systematic literature review in nursing: a step-by-step guide . 2nd edn. Maidenhead: Open University Press.
• Coughlan M and Cronin P (2016) Doing a literature review in nursing, health and social care . 2nd edn. Los Angeles: Sage.
• De Brún C, Pearce-Smith N, Heneghan C, Perera R and Badenoch D (2014) Searching skills toolkit: finding the evidence . 2nd edn. Chichester: Wiley Blackwell / BMJ Books.
• Hewitt-Taylor J (2017) The essential guide to doing a health and social care literature review . London: Routledge. 

Critical Appraisal subject guide

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Literature searching and finding evidence

Literature searching or 'literature review'.

• Use the PICO or PEO frameworks
• Establish your Inclusion and Exclusion criteria
• Find related search terms
• Subject Heading/MeSH Searching
• Select databases to search
• Structure your search
• Search techniques
• Search key databases
• Manage results in EBSCOhost and Ovid
• Analyse your search results
• Document your search results
• Training and support

For assignments , projects and dissertations you will need to do a literature search:  find existing literature and information about your chosen topic to use as evidence in support of arguments or points you make.

You may also be asked to produce a literature review:  summarising and analysing relevant literature you have found through your research. In a literature review, the literature itself is the main subject of discussion. The aim of a literature review is to show you have identified and examined the key research on a particular topic or question.

• Am I the only one struggling to write a literature review? (Video) Watch this video which provides an overview of writing an effective literature review.

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• Last Updated: Oct 2, 2023 12:27 PM
• URL: https://libguides.city.ac.uk/SHS-Litsearchguide

Literature Review: Purpose of a Literature Review

• Literature Review
• Purpose of a Literature Review
• Work in Progress
• Compiling & Writing
• Books, Articles, & Web Pages
• Types of Literature Reviews
• Departmental Differences
• Citation Styles & Plagiarism
• Know the Difference! Systematic Review vs. Literature Review

The purpose of a literature review is to:

• Provide a foundation of knowledge on a topic
• Identify areas of prior scholarship to prevent duplication and give credit to other researchers
• Identify inconstancies: gaps in research, conflicts in previous studies, open questions left from other research
• Identify the need for additional research (justifying your research)
• Identify the relationship of works in the context of their contribution to the topic and other works
• Place your own research within the context of existing literature, making a case for why further study is needed.

Videos & Tutorials

VIDEO: What is the role of a literature review in research? What's it mean to "review" the literature? Get the big picture of what to expect as part of the process. This video is published under a Creative Commons 3.0 BY-NC-SA US license. License, credits, and contact information can be found here: https://www.lib.ncsu.edu/tutorials/litreview/

Elements in a Literature Review

• Elements in a Literature Review txt of infographic
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